fix i18n for bindings (#14235)

Also-By: Jacob Laursen <jacob-github@vindvejr.dk>
Signed-off-by: Jan N. Klug <github@klug.nrw>

bundles/org.openhab.binding.siemensrds/src/main/resources/OH-INF/i18n/siemensrds.properties

@@ -1,7 +1,7 @@
-# binding
+# add-on
 
-binding.siemensrds.name = Siemens RDS Binding
-binding.siemensrds.description = This is the binding for Siemens RDS smart thermostats
+addon.siemensrds.name = Siemens RDS Binding
+addon.siemensrds.description = This is the binding for Siemens RDS smart thermostats
 
 # thing types